1. Field of the Disclosure
This disclosure relates in general to valves for hydrocarbon drilling, production and processing operations, and in particular to plug valves used for managing fluids associated with hydrocarbon drilling, production and processing operations.
2. Description of Related Art
Gate valves and ball valves can be used to manage fluids relating to hydrocarbon drilling, production and processing operations. However gate valves have cavities or voids which create pockets for sand and debris accumulation, and ball valves generally have open spaces around the ball. During operations of gate valves and ball valves, solid matter can accumulate in such voids and open spaces, which degrades their ability to seal or operate and eventually leads to failure.
It can be difficult to manufacture advanced rigid high pressure seals and some common valves instead currently use primarily elastomeric seals due to their conformability. However elastomeric seals alone can be both pressure and temperature limited and will result in plug valve assemblies that are not usually used in high pressure applications, in particular due to the extrusion of the elastomeric seals during operation.
It is also difficult to achieve metal to metal sealing around complex geometric shapes, such as a ball or cylinder. This is because the manufacturing of these parts to achieve conforming surfaces is more difficult, than say for flat gates and seats. As a result these valves are generally not used in bi-directional applications, or do not perform well at low pressures.
Furthermore, it is difficult to prevent sand or debris from entering the dynamic sealing areas for all types of valves. The ingress of sand or debris may prevent the valve from sealing properly. Therefore it is beneficial to permit only very small or zero clearances around the sealing surfaces.